A noisy exhaust fan isn't just annoying — it's telling you something is about to fail. Here's how to decode the sounds coming from your roof.
1. Squealing or Screeching
What it means: Belt slipping or worn. The belt is loose, glazed, or cracking. It's still technically working but losing grip — your exhaust CFM is dropping.
Urgency: Medium. The belt will snap within days to weeks. Schedule service this week.
Fix: Belt replacement. Contact us for pricing.
2. Grinding or Rumbling
What it means: Bearings are failing. Metal-on-metal contact inside the bearing housing. If you can feel vibration through the roof or hood, it's advanced.
Urgency: High. Failed bearings seize the shaft, which burns out the motor — turning a simple bearing job into a full motor replacement. Call today.
Fix: Bearing replacement. If you wait, motor replacement is significantly more expensive. Contact us for pricing.
3. Loud Vibration or Rattling
What it means: Fan wheel is out of balance. Usually caused by grease buildup on one side of the wheel, a broken blade, or loose mounting hardware. The vibration damages bearings, loosens ductwork connections, and can crack the fan housing.
Urgency: High. Unbalanced vibration causes cascading failures. Schedule within a few days.
Fix: Fan wheel cleaning and rebalancing, or blade repair. Check mounting bolts while you're up there. Contact us for pricing.
4. Clicking or Tapping
What it means: Something is hitting the fan blade — a loose piece of grease, a foreign object, or a blade rubbing the housing. Could also be a failing contactor or relay clicking on and off.
Urgency: Medium-low if intermittent, high if constant.
Fix: Inspection and foreign object removal. If it's a contactor, electrical repair is needed. Contact us for pricing.
5. Humming but Not Spinning
What it means: The motor is getting power but the shaft isn't turning. Either the belt is completely broken (most common), the motor capacitor has failed, or the motor windings are burned.
Urgency: Critical. Your exhaust is not working. No air is being removed from the kitchen. This is an emergency.
Fix: Belt replacement, capacitor replacement, or motor replacement depending on the cause. Contact us for emergency service.
The Bottom Line
Every noise is a warning. The repair cost goes up the longer you wait — a simple belt replacement today prevents a full motor replacement next month. The fan on your roof is running in the harshest conditions — heat, grease, rain, snow, UV exposure. It needs attention. Contact us for a quote.
True Commercial Service provides same-day exhaust fan diagnosis and repair across Union County, NJ. If your fan is making noise, we can usually fix it in one visit with parts on the truck.
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